staging: comedi: adl_pci6208: remove board attach noise

Remove the final dev_info() at the end of the board attach. This is
just added noise.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>